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fcntlThe module defines the following functions:
fd.
The operation is defined by op and is operating system
dependent. Typically these codes can be retrieved from the library
module FCNTL. The argument arg is optional, and
defaults to the integer value 0. When
it is present, it can either be an integer value, or a string. With
the argument missing or an integer value, the return value of this
function is the integer return value of the real fcntl()
call. When the argument is a string it represents a binary
structure, e.g. created by struct.pack(). The binary data is
copied to a buffer whose address is passed to the real fcntl()
call. The return value after a successful call is the contents of
the buffer, converted to a string object. In case the
fcntl() fails, an IOError will be raised.
fcntl() function, except
that the operations are typically defined in the library module
IOCTL.
FCNTL or IOCTL are missing, you
can find the opcodes in the C include files sys/fcntl and
sys/ioctl. You can create the modules yourself with the h2py
script, found in the Demo/scripts directory.
Examples (all on a SVR4 compliant system):
import struct, FCNTL
file = open(...)
rv = fcntl(file.fileno(), FCNTL.O_NDELAY, 1)
lockdata = struct.pack('hhllhh', FCNTL.F_WRLCK, 0, 0, 0, 0, 0)
rv = fcntl(file.fileno(), FCNTL.F_SETLKW, lockdata)
rv will
hold an integer value; in the second example it will hold a string
value.